The present invention relates to an improved copying machine which can implement three functions to serve as an ordinary copier, a facsimile transmitter and a facsimile receiver and is capable of selectively performing any of the three functions. The main scanning subsystem for facsimile transmission and reception is implemented by a laser beam deflector with a rotary polygonal mirror. The subsystem to scan an original for the ordinary copying function is used entirely as auxiliary scanning means including a light path with the exception of a copying lens. Hence scanning of a stationary original is rendered possible in both scanning operations in a facsimile mode and a copying mode, and two optical systems can be incorporated therein compactly.
In the prior art, a machine that is equipped with both an ordinary copying function and a facsimile function in one apparatus through application of a rotary polygonal mirror and an optical scanning means using laser technology has been proposed. Such a concept is presented in "Triple Function Box" in Technical Disclosure Bulletin Vol. 15 No. 10 (pp. 3259-3260) published in March 1973 by IBM Corporation. This prior art example, however, has a serious drawback in that the scanning technique for the copying machine is of moving platen type. This scanning method is shown in FIG. 1 where 1-a and 1-b herein which illustrates the initiation and termination of scanning respectively. As is clear in such a system a number of problems exist in the moving platen type. (1) At the termination of scanning, the platen protrudes from the copying machine by the distance A shown in FIG. 1-b, that is substantially equal to the entire platen size. This requires a larger space for installation. (2) Motion of the platen during copying operation causes a great inconvenience in practical use; and (3) High-speed scanning cannot be easily achieved since a large structure such as a platen cover is spread over the entire platen surface to support a platen glass and an original as large as JIS B4 size. It is to be moved horizontally with accuracy through a long travel distance equal to the dimension of the original.
Another drawback of this prior art example resides in the fact that the optical scanning system employing a rotary polygonal mirror and a laser and the projection lens system for the ordinary copying function are installed independently of each other in the machine and the two optical systems never share a common light path. Hence independent space is needed for each of the optical systems. Consequently, efficient use of the space in the machine becomes impossible to accomplish and it is difficult to configure the entire machine into a compact construction. Finally, the number of component parts increases to result in higher economic costs.
Yet another difficulty of the prior art is that, due to the requirement of independent light paths as mentioned above, the two optical systems must be adjusted individually and therefore render the assembly and adjustment overly complicated. Moreover, optical adjustment of the optical scanning means using a rotary polygonal mirror should be performed twice on both the original side and the photosensitive medium side, hence further complicating the procedure of optical adjustment.